A typical printing system includes a personal computer and a printer. The computer is connected to the printer by a communication link, such as a network. The computer is used to generate a document and to then send the document to the printer for printing. The document is sent in the form of page description language (PDL) commands. These commands describe the document. The printer receives these commands and responds by printing the document. “PCL” and “POSTSCRIPT” are each examples of a PDL. PCL is a trademark of the Hewlett-Packard Corporation. POSTSCRIPT is a trademark of Adobe systems incorporated.
Documents often include an image that occurs more than once in a document. For ease of discussion, such an image is referred to herein as a “form”. An example of a form may be a company letterhead or a company logo that occurs on each page in a document. An “instance” of the form refers to a particular one of the recurring images.
Current versions of POSTSCRIPT and PCL provide language specific constructs that allow a named sequence of PDL commands to represent a form. For ease of discussion, it will be understood that the phrase “named sequence” as used herein refers to a set of PDL commands that describe a form.
In general, the use of a named sequence can eliminate the need for a computer to repeatedly send the same set of commands to print each instance of a form in a document. As a result, the use of a named sequence can reduce the amount of data that need be transmitted to a printer in order to print a document.
PCL version 6.0, for example, allows for a named sequence to be defined using the “Macro” commands. A Macro is a group of PCL commands that is given a name in the form of an identification number. Once stored in the printer memory, a macro can be executed repeatedly by additional command that calls the identification number of the macro. Versions of the POSTSCRIPT language include similar capability.
The amount of time it takes to print a document is a significant factor in that printer's success in the marketplace. Thus, there is a strong interest in developing techniques to improve the printing speed of a printer. For purposes of this document, the phrase “printing speed” refers to the amount of time it takes for a printer to print a particular document. This time is measured from when the print job is first received by the printer until when the document is completely printed.
Accordingly, techniques that can improve the storage efficiency and speed at which a printer can process and print a named sequence are needed as this can increase the overall printing speed of a document.